Thank you.
I feel confident that the 285 on +15 will not rub. I am more concerned with how the front will look compared with rear, as the rear tire will be sticking out 7 mm past the fender, where as the front will be flush. That is why I was thinking the 275 in the back with +15 might look more balanced.
Regarding your comment about concavity. Here are pictures kindly provided by NoirG of the +25 rear wheel. Is this not concave enough?
